To the Editor,

Difficulty in removing an endotracheal tube (ETT) at the end of a procedure is a rare but dangerous and occasionally fatal complication of tracheal intubation and can be disconcerting to the anesthesiologist.1,2 As reviewed by Hartley and Vaughan, difficulty in extubation is typically caused by one of three fundamental mechanisms3: failure to deflate the ETT cuff,4 an excessive cuff size (which can lead to the cuff being jammed between the vocal cords), and adhesion of the ETT to the tracheal wall due to absence of lubrication.

We recently encountered this problem in an 81-yr-old patient (weight 70 kg, height 1.65 m) anesthetized for acute abdominal surgery. She was easily intubated orally with a cuffed 7.0-mm internal diameter ETT (Shiley™ Hi-Lo Oral/Nasal Endotracheal Tube Cuffed, Murphy Eye; Medtronic, Dublin, Ireland), which was fixed 19 cm at her lips after bilateral ventilation had been confirmed. During the surgery, we administered methylene blue through the nasogastric (NG) tube (10 mL diluted in 100 mL of isotonic saline) to find out if there was a duodenal perforation. After excluding duodenal perforation, intraoperative esophagogastroduodenoscopy (EGD) was performed to assess the state of the duodenum.

Following an uneventful surgical procedure (cholecystectomy for acute cholecystitis), on emergence from anesthesia, the pilot balloon was deflated in preparation for extubation. Nevertheless, there was resistance to pulling and it was not possible to remove the ETT. Extubation was not forced. Meanwhile, the intubated patient became agitated and had to be reanesthetized.

On direct laryngoscopy, a completely deflated cuff was visualized under the vocal cords and there were traces of dye in the patient's pharynx. We performed a computed tomography scan of the neck, which showed no damage to the trachea (Figure 1, panels a, b).

Figure 1
figure 1

Panels (a) and (b): A computed tomography scan of the patient’s neck showed no damage to the trachea. Panel (c): Inspection of the endotracheal tube following extubation showed traces of methylene blue on the cuff.

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After we ruled out damage to the trachea, we administered 3 mL of saline through the ETT. We then attempted to push the tube slightly and twist it gently and were able to pull the tube out smoothly. The patient was discharged from the recovery room without any problems.

We believe that several factors were involved in the present case. Excluding that a ring had formed on the ETT cuff, the first factor to consider was the presence of methylene blue. After extubating the patient, we noticed that there were traces of dye on the cuff (Figure 1, panel c). The methylene blue almost certainly came from the stomach, caused by prolonged use of the Trendelenburg position. We have noticed that methylene blue can create a sticky substance that may have caused the ETT cuff to adhere to the trachea, especially in the case of poor lubrication. The second factor concerns the intraoperative EGD, which probably favoured adhesion of the trachea around the tube due to a mechanical push of the esophagus on the trachea.

In conclusion, a combination of the presence of methylene blue on the ETT cuff, poor lubrication of the ETT, and the performance of intraoperative EGD may have caused the difficulty in extubating our patient. For cases involving methylene blue administration through an NG tube, we would therefore recommend careful attention, good cuff lubrication, and careful extubation of the patient with gentle movements of the ETT.